Phase-contrast x-ray imaging
Whereas conventional X-ray imaging is based only on attenuation of X-rays, X-ray phase-contrast imaging is also able to measure the subtler effects of refraction and ultra-small angle scattering. Thus, X-ray phase-contrast imaging permits visualization of soft-tissue structures that are not detectable by use of conventional X-ray radiographic methods, and typically delivers a much smaller radiation dose to the subject. Thus, these techniques offer great potential for a wide range of human, small-animal, and microscopic bioimaging applications.
Analyzer-based phase-contrast imaging (ABI) is a form of X-ray phase-contrast imaging that utilizes a semiconductor crystal, called an analyzer, to selectively measure certain angular components of the X-ray beam. A well-known method of ABI, called diffraction-enhanced imaging (DEI) uses two images taken by the analyzer system to produce images that separately depict the effects of attenuation and refraction.
Our group was the first to propose an improvement on DEI, called multiple-image radiography, in which three or more acquired images can be used to produce more accurate images than DEI, while also producing a third image, showing the effect of ultra-small angle scattering, an effect that depicts fine structures in the object being imaged. We also developed a further version called “extended DEI” (eDEI).
Our group derived many of the fundamental engineering principles of DEI and MEI, such as the noise properties, the physical interpretation of the images, optimal sampling methods, tomosynthesis and CT methods, and task-based performance evaluation.
Our Advanced X-ray Imaging Laboratory (AXIL), led by Prof. Brankov, has developed a prototype tabletop imaging system based on the analyzer concept, with a second-generation system under development as well.
J. G. Brankov and A. Zysk, “Analyzer-based phase-contrast X-ray imaging” in Emerging Imaging Technologies for Medicine, Taylor Francis/CRC PressBook, 2012.
M.N. Wernick, O. Wirjadi, D. Chapman, Z. Zhong, N.P. Galatsanos, Y. Yang, J.G. Brankov, O. Oltulu, M.A.
Anastasio, and C. Muehleman, “Multiple-image radiography,” Physics in Medicine and Biology, vol. 48, pp. 3875-3895, 2003.
G. Khelashvili, J.G. Brankov, D. Chapman, M.A. Anastasio, Y. Yang, Z. Zhong, and M.N. Wernick, “A physical model of multiple image radiography,” Physics in Medicine and Biology, vol. 51, pp. 221-236, 2006. [highlighted in Institute of Physics (IOP) Select]
J.G. Brankov, M.N. Wernick, Y. Yang, J. Li, C. Muehleman, Z. Zhong, and M.A. Anastasio, “A computed tomography implementation of multiple-image radiography,” Medical Physics, vol. 33, pp. 278-289, 2006.
C.-Y. Chou, M.A. Anastasio, J.G. Brankov, M.N. Wernick, E.M. Brey, D.M. Connor, Jr., and Z. Zhong, “An extended diffraction-enhanced imaging method for implementing multiple-image radiography,” Physics in Medicine and Biology, vol. 52, pp. 1923-1945, 2007.
M. N. Wernick, Y. Yang, I. Mondal, D. Chapman, M. Hasnah, C. Parham, E. Pisano and Z. Zhong, “Computation of mass-density images from x-ray refraction-angle images,” Phys. Med. Biol., vol. 51, pp. 1769-1778, 2006. [highlighted in Institute of Physics (IOP) Select]
C. Muehleman, J. Li, M. Wernick, J. Brankov, K. Kuettner, and Z. Zhong, “Yes, you can see cartilage with X-rays: Diffraction enhanced X-ray imaging for soft and hard tissues,” Journal of Musculoskeletal and Neuronal Interactions, vol. 4, pp. 369-370, 2004.
C. Muehleman, J. Li, Z. Zhong, J.G. Brankov, and M.N. Wernick, “Multiple-image radiography for soft tissue of the foot and ankle,” Journal of Anatomy, vol. 208, pp.115-124, 2006.
A.M. Zysk, A.B. Garson, Q. Xu, E.M. Brey, W. Zhou, J.G. Brankov, M.N. Wernick, J.R. Kuszak, and M.A. Anastasio “Nondestructive volumetric imaging of tissue microstructure with benchtop x-ray phase-contrast tomography and critical point drying,” Biomedical Optics Express, Vol. 3, Issue 8, pp. 1924-1932, 2012.
A. M. Zysk, J. G. Brankov, M. N. Wernick and M. A. Anastasio, “Adaptation of a clustered lumpy background model for task-based image quality assessment in x-ray phase-contrast mammography” vol. 39, Issue 2, pg. 906-912, Medical Physics, 2012.
M. A. Anastasio, C.-Y. Chou, A. M. Zysk, and J. G. Brankov, “Analysis of ideal observer signal detectability in phase-contrast imaging employing linear shift-invariant optical systems,” Journal Optical Society of America A, vol. 27, issue 12, pp. 2648-2659, 2010.